1. Field of the Invention
The present invention relates to the field of switching regulators.
2. Prior Art
Switching regulators such a buck converters provide an efficient way of converting a source voltage to a lower and regulated output voltage. However there are losses in such converters that determine the component requirements for such converters. The primary losses are in the switching transistors, and for a duty cycle in excess of 50%, the primary losses are in the high side switching transistor N1 of a typical buck switching regulator, shown in FIG. 1. This is true whether the switches N1 and N2 are on the controller chip, or are discrete devices.
Conventional buck converters are designed to operate at a fixed switching frequency, and accordingly are designed for the worst case of operating conditions for that frequency. In a typical application, there will be a maximum current requirement for a given output voltage and input voltage or input voltage range. Failure to satisfy these requirements may cause a system powered at least in part by the buck converter to overheat, malfunction, shutdown or reset.
In a battery charger, the requirements are not as severe, in that a dip in the output current of a battery charger will only cause an extension of the battery charging time to full charge.